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Not so many years ago the idea of a renewable energy CEO raking in billions, joining the ranks of oil barons, publishing tycoons, banking scions and other captains of industry would have seemed unlikely. The stereotype of the Birkenstock-clad hippie with dreams of a world powered by solar energy seemed to belong to the Age of Aquarius, not the dawn of the 21st century. This seemed especially so after the fall of communism ushered in a new era of capitalism and greed, all fueled to some extent by oil and gas, symbolized by the Bush years in the White House with their ties to American oil wealth, and the rise of the Russian energy oligarchs.

With the bull market in oil that followed the financial crisis in 2008, however, solar energy and to a lesser extent, wind, began to look more interesting to countries wanting to diversify away from expensive fossil fuels. The environmental movement and buy-in by governments that created incentives for utilities to use renewables, have also been factors in solar's ascent.

The increased demand for solar particularly in the United States and the Asia-Pacific region created a boon for makers of solar panels. Within a short time, the stock prices of those companies rose, and with them, the compensation paid to their top executives.

The growth of the solar industry is truly astounding, particularly in China, the world's solar leader. Between 2011 and 2012 the Chinese solar market grew by 500 percent. According to a 2014 report by Frost & Sullivan, a consulting firm, the global solar market earned revenues of nearly $60 billion in 2013. The firm estimates that by 2020 it will double to $137.2 billion.

With all this growth, somebody was obviously going to get rich, and it didn't take long for Oilprice.com to identify some of the biggest beneficiaries of the push toward renewables. The following are five of the world's most successful renewable energy business leaders and their net worth.

1. Li Hejun, Chairman, Hanenergy Holdings. $31.5 billion. After graduating as a mechanical engineer in 1988, Li Hejun borrowed RMB50,000 ($8,264) from a professor to start his own business. After several attempts at new ventures, including bottled water, electronic parts, mining and real estate, in 1994 he began investing in clean energy projects, according to the 2014 book China's Tycoons. Starting with a hydroelectric dam in his home province of Guandong, Li built six more dams in Yunnan, then expanded into wind farms and solar power. His company Hanenergy Holdings bought three Western, thin-film solar businesses in 2013 and a fourth, Alta Devices, in 2014. Li, who is China's richest man, added $3 billion to his wealth in March after Hanenergy's stock rose 36 percent in two days, according to Forbes.

2. Elon Musk, Founder/CEO, Space Exploration Technologies Corp., Tesla Motors (NASDAQ:TSLA). $12.2 billion. South African-born Elon Musk co-founded PayPal and was the company's chair and CEO before moving on to Tesla, the American manufacturer of high-end electric cars. In 2008 Tesla released the Roadster, a two-seat sports car, and a year later, the Tesla Model S, a stylish four-door sedan. But since Musk didn't yet have a factory, he sought one in Japan. As Wired tells it, Musk took a clandestine tour of the Toyota(NYSE:TM) factory, "[donning] a hard hat, a blue jacket, and plastic safety goggles and acted as inconspicuous as possible in the hopes of not being recognized." Impressed by the scale of the place, Musk offered $42 million and Tesla had its plant. A soaring stock price made Musk a wealthy man, and with $100 million, he founded SpaceX in 2002. The manufacturer of space launch vehicles in 2012 became the first commercial company to dock with the International Space Station and return cargo to earth via its Dragon spacecraft. In January SpaceX raised $1 billion from investors including Google and Fidelity, valuing the company at $10 billion, Forbes reported.

3. Wang Chuanfu, Founder, BYD Company. $5.3 billion. In 1995 Wang Chuanfu quit his job as a research chemist to set up BYD, which has been variously interpreted as "Build Your Dreams" or "Bring Your Dollars." Its first product was rechargeable batteries for mobile phones. But Chuanfu had greater ambitions and, in the early 2000s, he set out to become the world's largest electric car maker. BYD received a big boost in 2008 when Warren Buffett took a 10 percent share, but suffered later setbacks when car sales did not meet expectations and after a deadly accident involving one of its electric vehicles, according to China's Tycoons. The company is now the world's largest supplier of rechargeable batteries and also develops solar farms and battery energy storage stations.

4. Aloys Wobben, Founder/Owner, Enercon. $4.2 billion. Known as "Mr. Wind" in Germany, Aloys Wobben from a young age was fascinated with kites and had a large collection of wind toys. In 1984, the electrical engineer founded start-up Enercon, a manufacturer of turbines for windmills, and he turned the company into a global player in alternative energy. Opinionated and with a strong social conscience, Wobben has spoken out against the Iraq war and once said in an interview, "I wouldn't enjoy supplying wind turbines to a nation so that it can supply water for huge golf courses," referring to Enercon's lack of presence in the U.S. market.

5. Zhu Gongshan, Chairman, GCL-Poly Energy Holdings. $1.9 billion. Jiangsu province native Zhi Gongshan started out building coal-powered and biomass generators, with help from the powerful Poly Group. As GCL Group's largest shareholder, Poly Group had historical ties to the Chinese army and former Premier Deng Xiaoping. By the mid-2000s Zhu had a vision to produce polysilicon, the raw material for photovoltaics. He invested $1.15 billion in a unit to produce the material and signed long-term supply contracts with solar panel makers. In 2014 his company bought a 68 percent stake in Same Time Holdings, a manufacturer of printed circuit boards, which will invest in solar power plants.

Honorable mention: Rubens Ometto Silveira Mello, Chairman, Cosan, Raízen. $1.3 billion. The world's first ethanol billionaire began his rise to financial stardom as head of Cosan, a Brazilian sugar company. Nicknamed "the tractor" for sugarcane harvesting, Mello turned Cosan into one of Brazil's only privately controlled energy companies. It is one of the world's largest producers of sugarcane and ethanol.

By Andrew Topf of Oilprice.com. The Motley Fool recommends Google (A shares), Google (C shares), and Tesla Motors. The Motley Fool owns shares of Google (A shares), Google (C shares), and Tesla Motors. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.